Movies are typically distributed to theaters on heavy reels of film. When received, a set of reels containing a movie is moved to a projector room of a theater, and there the film on the reels is spliced together. Pre-movie content such as advertisements, movie trailers, theater announcements, etc., is also spliced to the movie prior to showtime. The process of distributing, receiving and preparing a movie for presentation can be an expensive and labor-intensive process.
Movies and pre-movie content can now be distributed, received and shown in digital format. When received, digital movies and digital pre-movie content can be stored as files on a hard disk of a computer system (e.g., a server), which in turn is coupled to a digital projector. At showtime, digital content is read from the hard disk and shown on a screen by the digital projector.
FIG. 1 illustrates in block diagram form relevant components of an exemplary digital cinema system 10 in which digital movies and digital pre-movie content can be shown to an audience. The combination of a digital movie and digital pre-movie content (e.g., a defined set of trailers, advertisements, announcements, etc.) will be referred to herein as a “playlist.” In digital cinema, a playlist is analogous to the final reel of film that a projectionist prepares for presentation, by splicing pre-movie content to a feature movie. As will be described below, digital cinema system 10 enables playlists stored in memory to be scheduled and shown at a certain time on a certain screen.
The digital cinema system 10 consists of a management server 12 coupled to a server database 24. The management server 12 is also coupled to content servers 20a-20c via Ethernet LAN 16. Digital projectors 24a-24c are coupled to content servers 20a-20c, respectively, via decoding processors 22a-22c. Digital projectors 24a-24c can show or project images onto screens 26a-26c, respectively. Digital cinema system 10 further includes a graphical user interface (GUI) 32 which is used to manage digital content, schedule playlists, and in general control components of digital cinema system 10 via Ethernet LAN 16. The GUI interfaces with a high resolution display 34 to implement functional features. The functional features include creating and scheduling a playlist.
A theater manager or other designated person may schedule when and where playlists are shown using GUI 32. More particularly, GUI 32 can be used to program into system 10 the start time and the auditorium where a playlist will be shown. When the scheduled time arrives, the management server 12 sends an instruction via Ethernet LAN 16 to the appropriate content server to begin showing the playlist stored locally within the content server. Before the playlist can be shown, however, the digital content of the playlist must be transferred from the server database 14 to local memory (e.g., a hard disk) of the content server via Ethernet LAN 16. As used herein, the phrase “transferring playlists” will mean transferring the digital content of playlists.
As one can appreciate, Ethernet LAN 16 is used to transmit playlists and instructions to, for example, initiate the playback of a playlist locally stored on a content server. The bandwidth of Ethernet LAN 16, however, may limit the ability to transfer a playlist or portions thereof from server database 14 to a content server's local memory or between local memories of a pair of content servers. The Ethernet LANs most commonly used in digital cinema systems provide transmission rates up to 10 megabytes per second (MBps). At 10 MBps, eight to nine hours is needed to transfer a 300 gigabytes playlist from, for example, server database 14 to one of the content servers 20a-20c or between the local memories of a pair of content servers 20a-20c. Moreover, the time it takes to transmit 300 gigabytes content of a playlist may be further delayed if the Ethernet LAN 16 is also used to transmit instructions, for example, to start movies previously loaded into content player servers.
The time needed to transfer a playlist using a 10 MBps Ethernet LAN may limit the ability to reschedule a movie on short notice. To illustrate, presume that a 300 gigabytes playlist is stored within a hard disk of content server 20a, and that the playlist is scheduled to be shown in auditorium 30a. Presume also digital projector 24a fails before showtime. In this situation, it would be desirable to move the playlist from content player server 20a to content player server 20b (or copy the playlist from database 24 to content player server 20b) via Ethernet LAN 16, and reschedule the start of the playlist for the same time, but in auditorium 30b. Unfortunately, if Ethernet LAN 16 is limited to transmitting data at a 10 MBps, the 8-9 hours it takes to properly move the playlist to content player server 20b may not allow theater management to reschedule the playlist in auditorium 30b at the same time the playlist was scheduled to begin in auditorium. Even if Ethernet LAN 16 operates at a 100 MBps data transfer rate, it may take 50 minutes to move the contents of a 300 gigabyte playlist to content player server 20b, a length of time that may not be conducive to rescheduling the start of the playlist to auditorium 30b. 
In addition to their relative slow data transmission rate, Ethernet communication links of Ethernet LAN 16 connected to servers 12 and 20a-20c, provide a metal based medium through which electronic signals can travel. Historically, this medium has been coaxial copper cable, but it can also be a twisted pair. Electrical signals propagate along a metal based communication link very quickly, but they weaken as they travel, and electrical interference from neighboring devices (fluorescent lights, large auditorium air conditioners, fans needed to cool digital projectors, or the high current square-wave voltage used to run the Xenon arc projector lamps or content player servers, for example) can scramble the signal. Illegal downloading of digital movies is another disadvantage with employing Ethernet LANs in digital cinema systems. Most portable computers today come equipped with an Ethernet network interface card (NIC) that can be used to easily tap into Ethernet LANs. Once tapped into the Ethernet LAN, such as Ethernet LAN 16, the portable computer can download digital movies from memories of devices (e.g., content servers 20a-20c), or download digital movies while they are being transferred via the Ethernet LAN.